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Message-Id: <1447721484-22548-1-git-send-email-dianders@chromium.org> Date: Mon, 16 Nov 2015 16:51:16 -0800 From: Douglas Anderson <dianders@...omium.org> To: John Youn <John.Youn@...opsys.com>, balbi@...com Cc: Yunzhi Li <lyz@...k-chips.com>, Heiko Stübner <heiko@...ech.de>, linux-rockchip@...ts.infradead.org, Julius Werner <jwerner@...omium.org>, gregory.herrero@...el.com, yousaf.kaukab@...el.com, dinguyen@...nsource.altera.com, stern@...land.harvard.edu, ming.lei@...onical.com, Douglas Anderson <dianders@...omium.org>, johnyoun@...opsys.com, gregkh@...uxfoundation.org, linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org Subject: [PATCH v3 0/8] dwc2: Fix uframe scheduler + speed up the interrupt handler quite a bit This series now effectively has two purposes: 1. Speed up dwc2 interrupt latency. 2. Start fixing up the microframe scheduler. ...the two things were separate series in the past but they ended up running into each other, so now they're combined. To summarize what we have here: 1. usb: dwc2: rockchip: Make the max_transfer_size automatic No brainer. Can land any time. 2. usb: dwc2: host: Get aligned DMA in a more supported way Although this touches a lot of code, it's mostly just deleting stuff. The way this is working is nearly the same as tegra. Biggest objection I expect is that it has too much duplication with tegra and musb. I'd personally prefer to land it now and remove duplication later, but up to others. Speeding up interrupt handler helps with SOF scheduling, so this is not just a dumb optimization. 3. usb: dwc2: host: Add scheduler tracing Useful for patches below. 4. usb: dwc2: host: Rewrite the microframe scheduler Seems hard to believe this would make things worse since the old scheduler is easy to break. Certainly microframe scheduler isn't amazing, but small steps, right? 5. usb: dwc2: host: Keep track of and use our scheduled microframe Needs review, but seems simple to me. Maybe doesn't fix everything, but fixes some things... 6. usb: dwc2: host: Assume all devices are on one single_tt hub Questionable, but maybe worth landing it? 7. usb: dwc2: host: Add a delay before releasing periodic bandwidth Pretty much the same patch I sent before, just rebased. 8. usb: dwc2: host: Giveback URB in tasklet context Simple and a nice speedup assuming it doesn't break anything. My belief is that our scheduler is already broken enough that things aren't made worse by this patch (and lots of things are made better by speeding up the interrupt handler and not mising SOFs), but welcome other testing and opinions. === Below is discussion of some of the speedup stuff. === The dwc2 interrupt handler is quite slow. On rk3288 with a few things plugged into the ports and with cpufreq locked at 696MHz (to simulate real world idle system), I can easily observe dwc2_handle_hcd_intr() taking > 120 us, sometimes > 150 us. Note that SOF interrupts come every 125 us with high speed USB, so taking > 120 us in the interrupt handler is a big deal. The patches here will speed up the interrupt controller significantly. After this series, I have a hard time seeing the interrupt controller taking > 20 us and I don't ever see it taking > 30 us ever in my tests unless I bring the cpufreq back down. With the cpufreq at 126 MHz I can still see the interrupt handler take > 50 us, so I'm sure we could improve this further. ...but hey, it's a start. This series also shows big speed improvements when testing with a USB Gigabit Ethernet adapter. Previously the tested adapter would top out at about 15MB/s. After these changes it gets about 23MB/s. In addition to the speedup, this series also has the advantage of simplifying dwc2 and making it more like everyone else (introducing the possibility of future simplifications). Picking this series up will help your diffstat and likely win you friends. ;) === Steps for gathering data with ftrace: cd /sys/devices/system/cpu/cpu0/cpufreq/ echo userspace > scaling_governor echo 696000 > scaling_setspeed cd /sys/kernel/debug/tracing echo 0 > tracing_on echo "" > trace echo nop > current_tracer echo function_graph > current_tracer echo dwc2_handle_hcd_intr > set_graph_function echo dwc2_handle_common_intr >> set_graph_function echo dwc2_handle_hcd_intr > set_ftrace_filter echo dwc2_handle_common_intr >> set_ftrace_filter echo funcgraph-abstime > trace_options echo 70 > tracing_thresh echo 1 > /sys/kernel/debug/tracing/tracing_on sleep 2 cat trace === NOTE: This series doesn't replace any other patches I've submitted recently, it merely adds another set of changes that upstream could benefit from. Changes in v3: - scheduler tracing new for v3. - The uframe scheduler patch is folded into optimization series. - Optimize uframe scheduler "single uframe" case a little. - uframe scheduler now atop logging patches. - uframe scheduler now before delayed bandwidth release patches. - Add defines like EARLY_FRAME_USEC - Reorder dwc2_deschedule_periodic() in prep for future patches. - uframe scheduler now shows real usefulness w/ future patches! - Keep track and use our uframe new for v3. - Assuming single_tt is new for v3; not terribly well tested (yet). - Moved periodic bandwidth release delay patch later in the series. Changes in v2: - Add a warn if setup_dma is not aligned (Julius Werner). - Totally rewrote uframe scheduler again after writing test code. - uframe scheduler atop delayed bandwidth release patches. - Periodic bandwidth release delay new for V2 - Commit message now says that URB giveback change needs delay change. Douglas Anderson (8): usb: dwc2: rockchip: Make the max_transfer_size automatic usb: dwc2: host: Get aligned DMA in a more supported way usb: dwc2: host: Add scheduler tracing usb: dwc2: host: Rewrite the microframe scheduler usb: dwc2: host: Keep track of and use our scheduled microframe usb: dwc2: host: Assume all devices are on one single_tt hub usb: dwc2: host: Add a delay before releasing periodic bandwidth usb: dwc2: host: Giveback URB in tasklet context drivers/usb/dwc2/core.c | 21 +-- drivers/usb/dwc2/core.h | 20 ++- drivers/usb/dwc2/hcd.c | 177 +++++++++---------- drivers/usb/dwc2/hcd.h | 30 ++-- drivers/usb/dwc2/hcd_intr.c | 73 +------- drivers/usb/dwc2/hcd_queue.c | 407 ++++++++++++++++++++++++++++++------------- drivers/usb/dwc2/platform.c | 2 +- 7 files changed, 416 insertions(+), 314 deletions(-) -- 2.6.0.rc2.230.g3dd15c0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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